For Cougar Mountain Software Support's
Professional Version (V2012, V2011, V2010, V2009, V12-V6)

out₂EM Outlook-winmail.dat
For Microsoft's Outlook (all versions)

QUESTION:  My attachments from outlook go to AOL users as a win.dat file, which can not be opened. I can send the same message attachment from web AOL and it's ok. Outlook changes the attachment to win.dat. How can I fix this?

ANSWER:   I think you mean winmail.dat.
Change your message format from Rich Text to either Plain Text or HTML.